3(2-cyclopentenyl)-2-methyl-4-oxo-2-cyclopentenyl chrysanthemumate insecticide and process of making it



3(2-CYCLOPENTENYL) -2 METHYL-4-OXO-2- CYCLOPENTENYL CHRYSANTHEMUMATE gfiigIClDE AND PROCESS OF MAK- Howard RrGuest and Harry A. Stansbury, Jr., South Charleston, W. Va., assignors to Union Carbide Corporation, a corporation of New York No Drawing. Application June 23, 1953 Serial No. 363,688

7 Claims. 01, 1,6 7-7-30) This invention relates to insecticides closely related to those found in pyrethrum flowers, Chrysanthemum United States Patent "ice ' The application to this alcohol and this acid ofconventional procedures for forming an ester, involving as they do elevated temperatures and long reaction periods, results in deterioration of the cyclopentenolone molecule and poor yields of allethrin. The process suggested by LaForge and others (J. Org. Chem., vol. 12, pp. 199-202 (1947); J.-Chem. Soc, (1950) pp. 3552-63) employs the cinerariaefolium. More particularly, it is concerned with 3-(2-cyclopentenyl)-2-methyl 4 oxo 2 cyclopentenyl chrysanthemumate as a new composition of matter. The structure of this ester, to which the name cyclethrin has been applied, can be represented graphically lowing formula:

(ona),o=ono'no on n,o--o='o 0 CO -O-H --C v a w I v H v I 00H; CH1- H1 3 -(2-cyclopentenyl)-2-methyl-4-oxo-2-cyclopentenyl chrysanthemumate I I The invention is concerned also with the process of making the ester and with certain intermediates employed in the process, as new compositions of matter.

on=on One of thelargest uses for; pyrethrumtoday is,fo'r the by the folto 0.25 percent by weight for ahousehold spray. Because of the high cost of pyrethrins and because the action of pyrethrins tends, at use levels, toward paralysis rather than outright killing, they are supplemented with rotenone, thiocyanates, DDT and related materials to provide kill. Such mixtures give both kill and knockdown.

Until the synthesis of .allethrin in thela'boratories of the Department of Agriculture, pyrethrum was unique in its rapid paralytic properties and freedom from hazard to mammalian organisms and the only material of its type which could be used to provide rapid knockdown (paralysis) of flies. Two of the active constituents of pyrethrum flowers are esters of substituted 3-methyl-2-cyclopenten-4- ol- 1 ones and chrysanthemummonocarboxylic acid. In

the procedure employed for the synthesis of allethrin,

acid chloride made by the action of thionyl chloride upon the acid. The acid chloride in turn is reacted with the cyclopentenolone in the presence of pyridine to give allethrin. A number of difiiculties over and above those arising out of the corrosive nature of the thionyl chloride and the noxious qualities of the sulfur dioxide and hydrogen chloride evolved are encountered in this final step of making allethrin. For instance, certain coproduct alcohol impurities present in the 2-allyl-3-methyl-2-cyclopentem 4-o1-l-one are also esterified by the acid chloride treatment. The resulting ester impurities in the allethrin are of low insecticidal activity and very difiicult to remov'e from the allethrin. In addition, sulfur and chlorine compounds'of unknown structure are formed and remain as impurities in the allethrin. In this connection, it is relevant to note that there is a'definite disinclination on the part of the Federal Food and Drug Administration toallow more than traces of such impurities in material which is represented for use as a safe insecticide. v

The 'difiiculties and shortcomings of the acid chloride procedure have beenobviated by the use of chrysanthemummonocarboxylic acid anhydride in-the esterification step for the production of allethrin and other esters. This improvement is the subject of the copending application Serial No. 299,729, filed July 18, 1952,"no'w U'.S. Patent 2,768,965;

By reason of the numerous steps required for the synthesis of chrysanthemum nionocarboxylic acid and 2-allyl- 3-methyl-2-cyclopenten-4-ol-l-one, andalso thecompligated nature of the operations, allethrin is and is likely to remain a high cost chemical for use in household-type oil sprays. Currently, the price of allethrin is about threefifths the price of pyrethrins. Pyrethrins and allethrin, by themselves, in household-type oil sprays are capable of kill, as Well as knockdown of insects, such as flies and roaches, if used in sufficient amount. From a practical, economic viewpoint, this is too expensive. Although the annoyance from flies is removed for a time when they are no longer capable of flight, an amount of pyrethrins or allethrin sufiicient to provide knockdown is not suflicient to kill. With roaches also, an amount of pyrethrins or allethrin insufiicient to kill is sufficient to activate them so that they will come out into the open where they can be sprayed directly with chemical for a kill. To bring down the cost of the sprays, they have to be fortified either i with another toxicant or killing agent, such as DDT or chrysanthemummonocarboxylic acid and 2-allyl-3 methyl- C CH 5 Ohrysanthemumaallyl-s-methym-cyclomouoearboxylic acid penten-i-ol-l-one OH1G O 4:611, wan a 4' methoxychlor, for instance, or with a synergist to extend or broaden their action or both. 4

The scarcity of pyrethrum during World War II stimulated the search for and development of addition materials which would improve the efficiency of the pyrethrins. To these addition materials which, of themselves, have little or no value as insecticides, the terms activators, extenders, and synergists have variously been applied. One of the earliest synergists developed for pyrethrins is N-isobutylundecyleneamide introduced about 1938. Sesame oil ofv which the active ingredient, sesamin, was found to be a synergist for pyrethrins, was discovered (U.S. Patent 2,202,145; 1940) at about this same time. The knowledge acquired about the structure of sesamin led to the-synthesis of related compounds, such as piperonyl butoxide, piperonyl cyclonene, napropylisome, and sulfoxide, which are the most commonly used 'pyrethrin synergists.

Other less efiective synergists are N-(2-ethylhexyl)-bicycloheptenedicarboxamide, poly- 3 oxypropylene glycol monobutyl ether of about 800 average molecular weight (viscosity, 240 to 260 S.U.S. at 100 F.), and the pinene ether of ethylene glycol.

As in the case of pyrethrum, efforts have been made to extend the insecticidal usefulness of allethrin. Although allethrin currently is not as costly as pyrethrum, on the other hand it is not capable of being as highly activated or synergized by the available pyrethrum synergists, as is pyrethrum.

Our new ester is more effective than are other pyrethrum replacements in activated or synergized compositions, as evaluated by standard tests against household pests, for instance. It is more effective also against ectoparasites of animals. In addition, it can be used to protect food products such as wheat and corn from insect attack. The number of chemicals available for this use is quite limited because of the dangers from residues left in the final food product consumed by humans and other animals. Because of the freedom of our new ester, cyclethrin, from mammalian toxicity, it can be used to advantage for these purposes.

The synthesis of our ester, cyclethrin, involves a number of steps, the reactions of which can be illustrated by the following scheme of equations:

STEP 1 Hydrogen chloride is caused to add to cyclopentadiene, which is a relatively inexpensive starting material, to form 2-cyclopentenyl chloride:

CHzCH Oyclopen- Hydrogen 2-cyclopcntenyl tadlene chloride chloride STEP 2 2-cyclopentenylacetone is formed by the reaction of sodium acetoacetic ester with the Z-cyclopentenyl chloride from Step 1, followed by ketonic cleavage.

CH=CH COCH Sodium CH CH COCHg NaOH I ethoxide I first; CHCl-i-HGNa CHOH (l: I then Hg- H; COOEt CHP H, COOEt HZSOA 2-eyclo- Sodium Alpha- (2-cycl0pentenyl) pentenyl acetoacetlc acetoacetlc ester chloride ester CH-CHgC O OH -kit OH O Hg Hg 0 O 2 Z-cyclopentenyl acetone STEP 3 Ethyl 4-(2-cyclopentenyl)-3-ketobutyrate is made by reaction of diethyl carbonate with the Z-cyclopentenyl acetone product of Step 2.

CH=$H H (IJHCH C 0011 (3 11 00 00 11 GHQ-CH1 2-cyclopentenyl Diethyl acetone carbonate CHOH C O CH C O 0 H; 0 H J H,

Ethy 4-(2-cyclopentenyl) B-ketobutyrate STEP 4 Pyruvic aldehyde is reacted with the ethyl 4-(2-cyclopentenyl)-3-ketobutyrate product of Step 3 in the presence of dilute aqueous alkali metal hydroxide to form 6-(2-cyclopentenyl)-3-hydroxyhexane-2,S-dione. The cster'is saponified to the sodium or potassium salt of the corresponding acid, which salt in turn condenses with the pyruvic aldehyde.

0 H: C H

CHCH COCH ii HOCOCH; 0 H7CH, H I

4-(2-cyclopentenyD- Pyruvic 3-ket0butyrlc acid aldehyde CH=OH HCH C-CILOHOHG OH; C O; H;- H3 H 6-(2-cyclopenteny'l) -3-hydroxyhexane-2,5-dlone STEP 5 The product of Step 4 is treated with dilute sodium hydroxide to form 2-(2-cyclopentenyl)-3-methyl-2-cyclopenten-4-ol-l-one.

0 co on, (HJ (D CH=CH -0H, CHFCE orL-brn 1 on-c o \(D/ onhon 0=ocnon GET-CH corn 2-(2-cyclopentenyl) -3-metl1yl- 2-cyclopenten-4-ol-1-one STEP 6 Finally, the cyclopentenolone product of Step 5 is treated to form the ester of dl-cis and dl-trans chrysanthemummonocarboxylic acid, preferably through the anhydride.

6-(2-cyclopententenyl) -3- hydroxyhexane-2,5-dionc Cyclethrin is a mixture of isomers, including four racemic forms or eight optical and geometric isomers. These isomers have not yet been isolated and evaluated.

While it might be possible, on the basis of a graphic representation of structure, .to regard our new ester as similar to allethrin. except for a 2-cyclopentenyl group in a position corresponding to that occupied by an allyl group in allethrin, such a view would be an oversimplification, unwarranted by the facts. Even were it possible to employ allethrin as a startingmaterial for the preparation therefrom of other compounds by the direct substitution of the allyl group, it doesnot follow that all of the products would exhibit the same useful biological activity. For instance, according to our studies and information, the following esters of chrysanthemummonocarboxylic acid are inferior in insecticidal activity or value:

3- (2 -butenyl)-2methyl-4-oxo-2-eyclopenteny1 chrys'anthemumate H-ehrysanthemumyl O 0-O H2 --O-chrysanthemumyl CCH;

" 3- (a cyclohexenylmethyl) -2-methyl-4-oxo-2cyclopenteny1 ehrysanthemumate v 6- (3-al1yl-2-methyl-4-oxo-2-cyclopentenyl) -3,6-dioxahexyl I v chrysanthemumate INQ- 0 I' "0 0-011, I onFonor-nh on-o CH;CH;CH;O chrysanthemnmy1 CCH;

3-(3 ally1-2-rnethyl-4 oxo-2 eyclopentenyl)-3-oxa1sropy1 I p chrysanthemumate 3 Biological testing of cyclethn'n, unsynergized, reveals that it is of the same order of effectiveness as furethrin (3-furfuryl-2-methyl-4-oxo 2-cyclopentenyl chrysanthemummonocarboxylate), unsynergized; and that both are equal to allethrin, all unsynergized. It reveals also that those synergistswhich are superior in efiectiveness with pyrethrin can also be used as synergists for cyclethrin. In general, slightly higher knockdown is obtainable with synergized pyrethrin than with cyclethrin synergized with the same synergists.

However, when synergized cyclethrin is compared with synergized allethrin onlyone-half as much cyclethrin is required with sulfoxide or with n-propyl isome; only one-third as much cyclethrin with piperonyl buto'xide and only one-half to two-thirds as much with sesame oil extractives.

.jAnother advantage pr cyclethrin is. that it is even less toxicto mammals on a direct'concentrat-ion basis than is ,alle'thr'in. According to one set of tests, undiluted cyclethrin (95.6 percent purity) has an LD-50 for rats I in the neighborhood of 1.4 grams per kilogram as compared with 0.34 gram per kilogram'for allethrin. Ac cording to another set of tests, the LD-SO for cyclethrin fed to male albino rats by intubation is 1.78 grams per kilogram. Fed as a dilution in Bayol D, the toxicity of cyclethrin is much less. Forinstance, at a concentration of 10 percent by weight in Bayol D, 3.98 grams per kilogram of cyclethrin killed only one of five rats While 2.0 and-1.10 *gram .per kilogram has allowed survival. Similarly, at a concentration of percent by weight in Bayol D, the LD-50 for male albino rats is. 4.9 grams per kilogram on the basis of the active ingredient.

l For comparison, theLD-SO dose for-diluted allethrin at a 10 percent concentration in Bayol D-is 0.90 gram glycol monobutyl ether having a structure asensss to be of the order of abouton'e-fifth as toxicias'fallethrin for rats in single oral doses on a directconcntration' basis, and still less at actual use levels.

Compounds which arevus eful as synergists in combination with cyclethrin are:

A. Piperonyl butoxide which is a technical grade of the 3,4-methylenedioxy 6-propylbenzyl ether of diethylene as represented by the following graphicformulaz;

.. Cam,

O OHgO 03H) 03H) 04H.

Compounds closely related to the above amount to about 20 percent by weight of the piperonyl-butoxide. I i

B. Normal-propyl isome which is the name given to di n propyl 2 methyl 6,7 methylenedioziy 1,2,3, 4-hexahydronaphthalene-3,4-dicarboxylate. Its structure canbe represented by the following graphic'formula:

anon mc H \O Y HC0003H1 orm lnona s=o 68H".

E. N-isobutyl unde'cylene amide, having the general formula 4 F. Pinene ether of ethylene glycol, having the empirical formula G. Piperonyl cyclonene, which is a mixture of 3-isoamyl 5 (3,4 methylene dioxyphe'nyl) 2 cyclohexe none and its 6-carbethoxy derivative H. Butoxypolypropylene glycol which is name we l ueQu ee -QI n r we: a

7 ing a viscosity of about 100 S.U.S. at 100 F. and an average molecular weight of about 800.

I. Su1fone, whi'ch is the name given to normal octylsulfone of, isosaphrole.

I. Synergist 264 which is the number assigned to N- (2 ethylhexyl) bicyclo [2.2.1] 5 heptene 2,3 dicarboximide.

K. Sesame oil isthe name given to the oil from Sesamum indicium of which about 0.25 percent is sesamin. The structure of sesamin can be represented graphically by the formula:

GH -O Of the eleven synergists named, sulfoxide and piperonyl butoxide are preferred.

Cyclethrin concentrates, containing in addition to cyclethrin other biologically active materials such as, for instance, polyoxypropylene glycol monobutyl ether having an average molecular weight of about 800 (known commercially as Crag brand fly repellant); beta-butoxybeta-thiocyanodiethyl ether and a mixture of the betathiocyanoethyl esters of higher fatty acid having to 18 carbon atoms (known commercially as Lethanes); terpene thiocyanoacetates (known as Thanite-Isobornyl Acetate); methoxychlor; and a synergist can be used to protect livestock from such ectoparasites as flies, lice and ticks. Illustrative of such a concentrate would be a formulation containing the ingredients in the following relative proportions by Weight.

Parts by Weight cyclethrin 0. 1 to 10 0 1 to 10 polyoxypropylene glycol monobutyl ether (av.

I11 wt. 800) 20 to S0 20 to 80 the like; or it can be applied to agricultural crops to prm tect against insect attack. Specifically, beans, corn, cabbage, apples and apple trees, grapes and the like can be protected from worms, beetles, aphids and'spiders. Similarly, it can be sprayed on such surfaces as the interior of grain bins or elevators to kill. insects attacking. cereal grains, or it can be applied directly on cows or other livestock to protect against fly attack. Still further, these same concentrates when diluted either with oil or water can be applied to such packaged goods as cereals or tfiour in cloth or. paper containers to protect against insect penetration and infestation. Good results have been obtained with cyclethrin concentrates having the following compositions:

Cyclethrin with synergists and a propellant can also be used in aerosols or pressurized sprays to kill insects such as flies, moths, mosquitoes, bedbugs, ants, roaches, confused flour beetles, silverfish, and the like. Such an aerosol or pressurized spray can contain in addition one or more of the halogenated toxicants such as DDT, methoxy chlor or Strobane, for instance, or thiocyanates or thiocyanoacetates and either with or without a solvent such as methylated naphthalenes, petroleum distillates and the like, if desired. Illustrative of a suitable aerosol or pressurized spray is the following formulation:

Pressurized spray Parts by weight Cyclethrin 0.01 to 6:0 Synergist 0.05 to 10.0 Toxicant 1 0.0/to 6.0 Polyoxypropylene glycol monobutyl ether 2 0.0 to 55.0

Solvent propellant to make a total of parts by Weight of spray.

DDT; methoxychlor; Strobane; thiocyanates; thioeyam acetates.

Viscosity at 100 (3., 250 S;U.S.; av. mol. wt. 800. 8 Freon 11 Freon 12.

Our new insecticide, cyclethrin, can also be used in dry formulations especially adapted for protection of cereal grains and flour against insect infestation in combination with inert dust-type carriers such as wheat flour, kaolin, talc, pyrophyllite, diatomaceous earth, kieselguhr, ben tonite, ground walnut hulls, ground sawdust and the like. Illustrative of a suitable composition for this purpose is a formulation as follows:-

Grwin protectant Parts :by weight Cyclethrin 0.02 to-IO.-5 Synergist 1.0 to 5.0 Inert dust-type carrier, remainder to make 100 parts.

Total 100.0

The following examples are illustrative.

asersss EXAMPLE 1 Port (a).-An hydrous hydrogen chloride was added to a mixture comprising 99 grams (1.5 mols) of monomeric The mixture was maintained at a temperature during the addition which was continued for a period of about one hour until a gain in weight of about 58 grams was, obtained. After the carbon tetrachloride had been distilled ofi at atmospheric pressure, there was obtained 138 grams (1.35 mols) of 2-cyclopentenyl chloride distilling at a temperatre of 52 C.53 C. at an absolute pressure of 100 millimeters of mercury. The yield was 90 percent of theory. v j Part (b).-Three hundred six grams of sodium ethoxide (4.5 mols) in the form of 1570 grams'of a 19.5 percent solution in ethanol were added gradually to 650 grams mols) of ethyl acetoacetate with stirring over a period of 30 minutes. The mixture was maintained at a temperature of 20 C. during the addition. After the mixture had been stirred for an additional period of one hour at 20 C., it was heated to, a temperature of 50 C. and 459 grams of Z-cyclopentenyl chloride (4.5 mols) were added over a period of 1.5 hours. To complete the reaction, the mixture was maintained at its refluxing temperature at atmospheric pressure for a period of 3 hours. At the end of this time ethanol was removed from the mixture by distillation at atmospheric pressure to a kettle temperature of 125 C. The residue, which contained ethyl 2-cyclopentenyl-acetoacetate, was cooled to 20 C. and 2500 grams of aqueous sodium hydroxide percent; 6.25 mols) were added over a period of 30 minutes. To complete the ketonic cleavage of the compound the mixture was stirred for a period of 4 hours while the temperature was maintained at 20 C. Next, 400 milliliters of aqueous sulfuric acid (50 percent) was added to reduce the pH of the mixture to 3.5. The mixture was treated with 200 milliliters of benzene and a distillation carried out at atmospheric pressure using a rectify ing column fitted with a decanter of 175 milliliters capacity filled with benzene. During the distillation, a total of one liter of water was fed gradually into the vapor line just before the condenser. The lower layer in the decanter was continually removed while the oil in the decanter was returned as reflux to the still. This procedure was continued until the bead temperature reached 68 C. with the result that all of the ethanol was removed from the system while all the 2-cyclopentenylacetone product remained in the still.

Upon distillation of the oil in the residue, to which was added the oil in the decanter, there was obtained 440 grams of Z-cyclopentenyl acetone having the following properties: boiling range at an absolute pressure of millimeters of mercury, 66 C. to 68 C.; specific gravity (/20), 0.940. Analysis of the distilled product for ethyl acetoacetate by the sodium methoxide procedure gave a value of 8.3 percent by weight. Analysis for ketone by the hydroxylamine procedure @gave a cyclopentenyl acetone content of 89.1 percent by weight after correction for the ethyl acetoacetate content. Because the boiling points of 2-cyclopentenyl acetone and ethyl acetoacetate lie very close, separation of the two compounds by fractional distillation is not readily accomplished. Upon removal of the ethyl acetoacetate from the 2-cyclopentenyl acetone, by saponification, the pure ketone had a specific gravity (20/20") of 0.934 and a refractive index (n of 1.4543. The yield of -2-cyclopentenyl acetone was 72 percent based on the 2-cyclopentenyl chloride, corresponding to an efliciency of 72 percent.

Part (e).Diethyl carbonate (2240 grams; 19 mols) was charged to a distillation kettle fitted with a refluxing condenser, and heated under a reduced pressure of 100 millimeters of mercury absolute at its refluxive temperature. Sodium ethoxide (185.6 grams; 2;73 mols) in the 10 form of a 19.3 percent solution in ethanol (776.4 grains) was fed into the kettle over a period of 2 hours while ethanol was being continually distilled. The total 'distillate collected was 1033 grams. After all'the ethanol 7' lfl/tt/liiimmw 77777717 77727 pin dium ethoxide in the diethyl carbonate in the still kettle, 340 grams of 2-cyclopentenyl acetone (purity, 91.7 per cent; 2.5lmols) were fed over'a period of two hours while the distillation was continued as before toremoye ethanol. The total amount of distillate removed in this step was 289 grams. The residue was then cooled to 25 C., acetic acid (174 grams; 2.9 mols) added, which was followed by the addition of 620 milliliters of water to dissolve the sodium acetate. The oil layer was sepa rated and distilled rapidly under reduced pressure. There was obtained 400 grams of ethyl 4-(2-cyclopentenyl)f-3-' ketobutyrate having a boiling range of 100 C. to 155 C. at an absolute pressure of 5 millimeters of mercury; By titration with sodium methylate in pyridine the purity was found to be 94.6 percent. Analysis of the'midfraction (183 grams) showed that it contained 82.4granis of product. The yield basedon the 2-cyclopentenyl acetone was percent. Part (d) .-Eight hundred nineteen grams of'ethylf4 (2-cyclopentenyl) -3-ketobutyrate, having a purity 'of 93.1 percent (3.89) mols) were added dropwise over a period of one hour to 2180 grams of a well-stirred aqueous solution of sodium hydroxide (9.5 percent; 5.18 mols) maintained at a temperature of 20 C. to 25 C. At the end of 16 hours, the solution was neutralized to apH of 7.5 with carbon dioxide. 1 4 Fifteen hundred grams of an aqueous "solution of pyruvic aldehyde (22.4 percent; 4.67 mols) which had been neutralized to a pH of 7with 26 grams of sodium bicarbonate was fed to the neutralized solution ofthe beta-keto acid over a period of- 1.25 hours whilejthe're action mixture was maintained at a temperature of25". C. To complete the reaction, the mixture was allowed to stand 21 hours and then extracted four times with successive l-liter portions of diisopropyl ether. The four extracts were combined andv stripped of volatile material to a kettle temperature of C. under a reduced pressure of 4 millimeters of mercury, absolute. Therewas obtained as a residue product 742 grams of 6-(2-cycloi pentenyl) -3-hydroxyhexane-2,5-dione which was fou'ndby analysis'to have a purity of 75 .8 percent. The yield was 7.4 percent based on the ethyl-4-(2-cyclopentenyl) 3 ketobutyrate. Part (e).Three hundred sixty-eight grams of 6 (2- cyclopentenyl) -3 hydroxyhexane-2,5-dione having a purity of 75.8 percent (1.42 mols) was fed dropwise over a period of 30 minutes to 3312 grams of a 2 percent aqueous sodium hydroxide, vigorously stirred and main tained at a temperature of 20 C. to 25C. After a period of 4 hours allowed for completion of the reaction, the mixture was saturated with sodium chloride andfour successive extractions were made, each with one-liter portions of diisopropyl ether. The four extracts were com bined, neutralized with 2 grams of acetic acid and distilled under reduced pressure. There was obtained 139 grarnes of a product fraction which distilled from a temperature of C. at an absolute pressure of 2.5 millimeters of mercury to a temperature .of C; at an absolute pressure of 5 millimeters of mercury.. This product was found by analysis to contain 72.8 percent of 2-(2-cyclopentenyl)-3-methyl-2-cyclopenten-4-ol l-one. The yield was 40 percent. Bart (f)...A.mixture was formed of 275 grams of Y2 (Z-cyclopenten) -4-ol-1-one (purity 70.8 percent; 1.094

mols), 156 grams of pyridine and 0.905 liter of ethanoL.

.To this mixture was added a solution of 183 grams of semicarbazide hydrochloride (1.64 mols) in 220 milliliters of water The mixture was allowed to stand 16 hours and at the end of that time the crystals of the semi-' carbazone which had formed were filtered and washed with 4 liters of water to remove chloride. Upon crystallizing the semicarbazone from ethanol, 181 grams of colorless crystals having a melting point of 208 C. to 210 C. were obtained. The yield of the pure semicarbazone of 2-(2-cyclopentenyl)-3-methyl-2-cyclopenten-4- ol-l-one was 71 percent.

A mixture of 181 grams of the pure semicarbazone (0.77 mol), 1.6 liters of water, 1.6 liters of diisopropyl ether and 1047 grams of potassium acid sulfate (7.7 mols) was stirred at 60 C. to 65 C. for a period of 2.5 hours. By that time all of the semicarbazone had dissolved which indicated that hydrolysis had taken place and was complete. The aqueous layer was separated and extracted three times with 200 milliliter portions of diisopropyl ether. The three extracts were combined with the oil layer from the hydrolysis and the whole washed with 200 milliliters of saturated sodium chloride solution. Upon distillation of the ether solution there was obtained 101 grams of 2-(2-cyclopentenyl)-3-methyl-2-cyclopenten-4-ol-1-one characterized by the following properties: boiling point at an absolute pressure of 1 millimeter of mercury, 131 C.; refractive index (n 1.5350; purity (by analyses for hydroxyl content), 96.7 percent. The yield based on the semicarbazone was 84 percent, with credit being taken for 17 grams of product contained in the mid-fraction and column holdup.

Part (g).--A mixture of 92 grams of 2-(2-cyclopentenyl)-3-methyl-2-cyclopenten-4-ol-l-one having a purity of 96.7 percent (0.5 mols), 168 grams of chrysanthemummonocarboxylic anhydride having a purity of 94.8 percent (0.5 mol) and 119 grams of dry butyl ether was refluxed at a temperature of 165 C. for a period of 4 hours. The solution was diluted with 42 grams of butyl ether and washed successively with 263 grams of 7.6 percent aqueous sodium hydroxide (0.5 mol), 0.25 liter of 2 percent aqueous sodium hydroxide (0.125 mol) and 0.25 liter of water. The washes were each extracted in sequence with a single 0.1 liter portion of dibutyl ether to minimize loss of product. The washed oil and extract were combined, stripped of volatile material at a kettle end temperature of 80 C. at a reduced pressure of 5 millimeters of mercury, absolute, and thereafter stripped with steam. There was obtained 162 grams of residue product characterized by the following properties: refractive index, (n 1.5120; specific gravity (/20 C.), 1.033; purity by the ethylene diamine method, 87.1 percent; acid content, as chrysanthemummonocarboxylic acid, 0.1 percent; and chrysanthemummonocarboxylic anhydride content, 0.2 percent. The yield based on the reactants was 88 percent, with credit being taken for 4.3 grams of product consumed in analysis of the reaction mixture for anhydride content.

A number of formulations were prepared in which cyclethrin prepared according to a procedure the same as or similar to those described in Example 1 was tested for efiiciency in admixture with a variety of compounds having a synergistic efiect, These formulations were tested by the Feet-Grady Method (Ofiicial Method of the Chemical Specialties Manufacturers Association). The results of these tests together with the comparison test results obtained with the Ofiicial Test Insecticide (herein referred to as OTI) and with allethrin formulations similarly synergized are given in the following examples:

EXAM P LE 2 Large group Peer-Grady results Percent OTI Difference Formulation N0. of Percent Knock- Tests Kill, down,

24 Hrs. 10 min Kill Knockdown A. cyclethrin 5 61. 3 91.2 +25 -28 B. 5 40. 0 90. 0 +4 -4. 0 OT 8 35.5 94.0

These test results show that the plus value for kill and the minus value for knockdown of the synergized cyclethrin compared with OTI are better by 21 and 1.2

percentage points, respectively, than a similar comparison of synergized allethrin with OTI.

EXAMPLE 3 Formulation A B OTI cyclethrin, milligrams 5O allethrin, milligrams-.. 50 pyrethrins, milligrams n-octyl sulfoxide ofisosafrole, mil grams 250 250 deodorized kerosene fraction, milliliters. 100 100 100 Large group Peel-Grady results Percent OTI Difference Formulation No. of Percent Knock- Tests Kill, down,

24 Hrs 10 min Kill Knockdown These test results show that the plus values for kill and knockdown of the synergized cyclethrin compared with OTI are better by 38 and 5.9 percentage points, respectively, than a similar comparison of synergized allethrin with OTI.

EXAMPLE 4 Formulation A B cyclethrin, milligrams. allethrin, milligrams... pyretbrins, milligrams. n-propyl isome, milligrams- 600 600 deodorized kerosene fraction, milliliters 100 100 100 By n-propyl isome is meant (di-n-propyl-2-methyl-6,7-methylene dioxy-l,2,3,4-hexahydronaphthalene-S,4-dicarboxylate.)

Large group Peel-Grady results The results of this test show that the plus value for kill for synergized cyclethrin compared with OTI is better by 18 percentage points than a similar comparison of synergized allethrin with OTI; while the knockdown is only slightly less favorable by 1.9 percentage point.

The results of this test, show that the value for or the. sesame oil-synergizedfcyclethrin, even thoughiminus compared with OTI, is better by +7 percentage points than a; similar comparison of synergized allethrin with OTI; while the knockdown is only slightly less favorable by -1 percentage point.

EXAMPLE 6 Formulation A B OTI e yclethrin," milligrams" 30 Ellethrin, milligram 30. pyrethrins, mliiigrams r 100 synergist 6266, milligrams i, 000 1,000 deodorlzed kerosene fraction, milliliters 100 100 100 OhemicaI identification: N-(hexoxyethoxypropyl)-bieyclo-[2.2.11- heptene-2,3-dicarboxim.ide.

Large group Peer-Grady results The results of this test show that the plu s values for' and knockdown of the synergized cyclethrin, compared with OTI, are better by 16 and 2.1 percentage points, respectively, than a similar comparison of synergized allethrin with OTI. I

. EXAMPLE 7 Formulation ,AV B QTI clethrin, milligrams. 51

'gfiethrin, milligrams. 51 pyrethrlns, milli rams 100 synergist264, mllligrams I fieodorized kerosene traction, millilite 100 Chemical identification: N-(Z-ethylhexyl)-bicyc1o-[2.2.1]-5-heptene- 2,3-dlearboximide.

Large group Feet-Grady results EXAMPLE 8 Tests were carried out on a formulation containing 'cyclethrin as an oil-base livestock spray in comparison with a commercial oil-base livestock spray containing pyrethrins. The proportion of ingredients present in the formulation was as follows:

Formulation A B O eyclethrin, milligrams"--. 15 pyrethrins milligrams 25 15 piperonyl butoxide, milligrams 200 120 120 polyoxypropylene glycol mouobutyl ether 5 5 Spray oil added to make up solutions to a volume of milliliters.

The tests were carried out on dairy cattle in a South 1 Atlantic State and ten cows were used for treatment by each formulation. The cows were sprayed twelve times and the sprays were applied at intervals of three to four days at a rate of two ounces per animal. The sprays were applied in mid-afternoon and counts were taken at noon on the following day, of horn flies (=h); stable flies (=8; and house flies (=H). The ratio of the fly species in total population was 50, 20 and 30 percent, respectively, for horn flies, stable flies and house flies.

' The results of these tests in terms of repellency are given in the following table:

Q Percent Repelleney at Repel- Fly Species lency for.

v Period,

24 hr 48 hr. 72 hr. Average 65. 7 55. 4 31. 8 50. 9 s A( m ins) s zi' re p e r 5 5 7. r p y yr 40. 0 35. 3 43. 1 39. 5 90. 0 76. 8 47. 8 71. 5 71. 5 63. 8 50. 2 61. 8 B mm) s 3; g i S 1'8 e 5. p y PST 57. 3 44. 5 48. 8 50. 2 88. 0 88. 1 74. 6 81. 6 74. 2 63. 0 52. O 63. 1 60.0 43. 0 0 34. 7 Spray 0 (cyclethrin). 74. 9 47. 1 52. 3 58.1 v 65. 2 41. 4 55. 5 54. 0 84. 7 88. 6 93. 7 89. 0

The above values for percentage repellency is based on the number of counts taken, as follows:

Fly Species 24 Hrs. 48 Hrs. 72 Hrs.

120 100 so 30 2o 90 so so 90 80 so 110 100 According to these tests, the synergized cyclethrin formulation as an oil-base live stock spray is shown to be more efiective in repellency against horn, stable and house flies than commercial formulations of synergized pyrethrins. It is to be noted that Spray C is superior to Spray B, and at'the same time cheaper than Spray B and, accordingly, Spray A. Thus, at current prices for the ingredients of the respective formulations, this increased eflectiveness with synergized cyclethrin is obtainable without increase in cost.'

315 EXAMPLE 9 Formulations employing the same proportions of ingredients as those of Example 8, except that deodorized kerosene was substituted for the spray oil of Example 8, were made as follows:

Formulation OTI A B G piperonyl butoxide, milligrams 200 120 120 pyrethrins, milligrams 100 25 15 Crag Fly Repellent, 1 milliliters 5 5 cyclethrin, milligrams 15 Deodorized kerosene to make 100 milliters of solution.

1 Polyoxypropylene glycol monobntyl ether.

Large group Peer-Grady test results for control of flies Percent Knockdown Percent OTI Formulation N0. of Kill, 24 difference Tests Hours and rating 3 min. 5 min. 10 min.

6 86. 1 90. 2 95. 2 67. 9 +31 AA 6 87.0 92. 6 96. 72. 3 +36 AA 6 80. 8 85. 4 93. 6 70. 3 +34 AA According to these tests, Spray C is as eiiective in knockdown and kill as Spray B, while at the same time it is less expensive.

EXAMPLE The efiicacy against the German roach was determined for cyclet'nrin alone, and for cyclethrin in combination with sulfoxide (n-octyl sulfoxide of isosafrole) as synergist.

Formulation, Series 1 Formulation 1 Cyclethrin,

milligrams Allethrin, milligrams Sulfoxide, milligrams 1 In addition, each of the solutions contained 0.02 milliliter of Triton; 5 milliliters of acetone, and the whole made up with water to a total volume of 0.1 liter.

A second series of tests were run employing the following formulations.

Formulation, Series 2 Formulation Cyclethrin,

milligrams Allethrin, milligrams Sulfoxide, milligrams The results in terms of the dosage required to kill 50 percent of the roaches in 24 hours are given in the following table.

Results, Series 2 Milligrams 10 Formulation for kill LD-5Q, 24

ours

A through E (cyclethrin) F through H (cyclethrin) 4. 5 1 I through M (allethrin) 3 9 N through P (allethrin) 2. 7

In both series, cyclethrin was synergized more ciao-- tively than allethrin. In the case of allethrin, only onehalf or less of the amount required unsynergized was saved by synergizing it, whereas in the case of cyclethrin it was possible to save from two-thirds to four-fifths of the amount required unsynergized.

EXAMPLE 11 The efiicacy against the bean aphid on nasturtiurn plants was determined for cyclethrin, alone, and cyclethrin synergized with sulfoxide (n-octyl sulfoxide of isosafrole), and synergist 6266 (N-(hexoxyethoxyprop'yl)-bicyc1o- [2.2.1]-5-heptene-2,3-dicarboximide). Similar tests were. also made with allethrin.

Allethrln, Milligrams Cyclet'nrin, Milligrams Sulfoxide, Milligrams 6266,

Formulation 1 1 In addition, each of the formulations contained 10 milliliters of seetone, an amount of emulsifier which was 10 percent of the total weight of toxicant (allethrin 0r cyclethrin, plus synergist when used), and water in an amount such as to make a total volume of 0.1 liter.

The resulting mixture was agitated and sprayed on potted nasturtium plants, each pot of plants being in-= fected with approximately 250 nymph and adult bean aphids. Potted plants were set on a revolving turn-table and milliliters of the milliliters of the formulation were applied from a De Vilbiss sprayer, model CH 62041, under a pressure of 40 pounds per square inch. Counts of dead aphids were taken twenty-four hours after treatment was applied. Dosage series tests were con ducted and the results plotted on a log probability scale.

18 the syfiergizea inaterial ea besaaiatefi graphically the results of Eiai'fifil'e 12 "g of from the curves thus obtained the amounts correspond- Milligrams for m ing to the kills and knockdowns for the synergized mawithinzimms tenal above. The amounts thus estimated are given in Formulation v the following table: LD750 L D-r95,

A through E (allethrln; 70v fgrouglhg ((alleltlziin 27 V20, 10 a W MWWMW.

Dug We 9 T111 10 89 Equivalent amount (milligrams) 6: N through P eyelethrin) 1 11 T w Qthrough s (allethrin) a 14. e??? P319593??? gva tthfi'ollglilgltlyfiltgiiti) g a r ,t i. V roug 8 6 l1 F l V 2 through BB (cyclethrin)-.. a: 9. a mmmatmn 24 1 %$i;;2;;.

According to the results of these tests, cyclethrin is alletlnin eyelethrin an'etmstye'iesn rendered more effective by the 'synergists than is 'allethrin, by a considerable factor. A1 le 5; p peronyl but0xide 200) EXAMPLE 12 A?) piperony1 11 o e A companson was made of cyclethm and al1ethr n'20 ls 1 gu t l gn, synerglst against houseflies in large group Peet-Grady tests. The B2 results, which are the average of five tests are given m 6266, the following table: csellethrin, 50; sultoxide,

05 805555515, BbTs'iiirBSfiZiT w v. Gonoentra- Percent Percent 25 'i" a arm to$3fi363:- *fii3i ours D2 (0 clethrin 50; nto l fl 1som e,250) P W '97-5. Va1i1e's-1n-mi11igram's are "iven "er 100 milliliters f d 0d iz d gg- 9&5 3o krossiefiaatron. g r P I 6 H8 91-4 100 26.6 89.6 l r ,50 14.7,. 88.1 1 50 1M 1 r'lihe flqs s qwv es9i.i asyn raaslnu nyae V a gized tox cant (allethr1n, s ynergiz ed v. unsynergized; cy- I1 if1fii1Ii'gf1-1d1ns' ar '100 milliliters ottoman in deodorized Rubens 3 le y e gl ed v. unsyne gized a ed 6 11 .16 forefraction. I I w g 5 going values, are as follows:

nal s ofiih anc o the'a ve resfultsj'shows no significant difference in the performance of allethrin Y and cyclethrin when usedjunsynergized againsfh'oiise flies. 1 K 15 5313555 EXAMPLE 13 smrgist' V. y g zr cyclethrin r mpai du i w yn ygw g allethrin eyclethrin alletlmn cyolethrin allethrinagainst houseflies -inlarge-group Feet-Grady r J t T synergism ere. p p ylbutoxidej (3 i$ i "II 31$ i 31%; -31? methylen'edioxy--propyl) benzyl butyldiethyleneglycol 3- a Y -P 1 ether), synerglst 6266 (N-(hexoxyethoxypropyl)-b1cyclon mp y 7 M a 7 6 2 1 32 [2.2.1]-5-heptene-2,3-dicarboximide), sulfoxide (n-octyl e... 4 .1 1q.2 :7 as s f x e fiso af o an .;n-pr9py.1- e (Qi- L'P IQPY I a 1 v 2-methyl-6,7-methy1e'rie dioxy-1,2,3,4-hexahydronauhthalene-3,4-dicarboxylate)'.;, o .7 v 7 According to the above results, oyclethrin in overall Formulation A1 A2 B1 B2 01 02 D1 D2 a1lthrln,1iiillfgrams 2'3 a0 eye1ethrln,. mil1igrams. 25 30 50 50- plperonylbutoxide, milligrams 200 200 synergist'6266' milligrams" moo 1,000 SulfOldde, milfiu-mms 250 '250 n-propylisommmilligmms... 250 260 deodorized kerosene traction, so r, .r

milliliters 100 100 100 s 100, I 10.0. 100 100 100 The results which are the average- 0f four tests are performance is ten times .rnore efieet-ive synergized than given-in the following table: unsynergized, as cornpared with allethrin in oyerall performancewhich is only four times moreefiective syner- :v a -w 12 1 ized than unsynergizd. For knockdown alone, cycle- Folmulatlon 5 4: a g thrin ,is four times more efie'ctive" synergiifed than M t unsynergized, whereas allethrin, for knockdown .alone is a; a. .s i only three times more effective synergized than 521 igaue lgn lu px emnyg i m igg 3 g unsynergrzed.

2 eyce rinpusvpiperony u o e t 7 B1 (allethrinplus synergist 626 L; 31.4 92.1 EXAMPLE 14 B2(eyclethrin.plussynergist 6266) 46.6 v 94.2 H a a, V a s c1 anethrin lu ssulr ng v Tests were conducted on the conrmon housefly using 3 g fi lf gfi gifg i gga 421.3 0 cyclethnn 1n aerosol formulations according to the ofiictal DZ-(cyclethrinplus n-propylisoule 63.4 92.8 spec1ficat1ons of the Standard Aerosol Test Method for I a a I v Flying Insects. Comparison tests were also carried "out 'I he anaount pfunsyriergized yyelethrin and unsynerusing allethrin'. Equal parts of dichlorodifiuoromethane s ze e'th int at: wnuldahe; rreauirc tqi iv th am (Freon and trlphlowfluoromethane QJ T d percent an kuo k ob ained bove w 15 128 Pa ts by w isht fseach of the formulations T Sovacide Synergist 6266 grams Synergist 264 Dosage for kill of Mexican Bean Beetle Larvae, milli- Results in terms of Cyclethrin,

grams Bayol D m ma 7 3 L7 3 Lzairar fl Q0 0 T n amnm m a w am 1& 3 u Am H H63 H63 Formulation of dead larvae were taken after a 72-hour exposure period. Dosage series tests were conducted and results Sulfoxide Formulation 1 plotted on log probability paper. 50 percent lethal dose (LD-SO) were as follows:

ndnnronrrnnmNon nsru O is aromatic petroleum solvent.

Piperonyl Butoxide ne, highly refined; Strobane is chlo- Sovacide 544- Strobane 1 In addition each formulation contained milliliters of acetone and The results are set forth in the following table:

Difierence from TOTA Test ingredients making up t chlorine, by weight' 0.4 ofi' chloroethane; Bayol D is kerose Oyclethrin Allethrin DDT Percent Percent Referred Large group Feet-Grady results remaining parts by weight of Formulation the formulations were as follows:

Norm-DDT is dichlorodiphenyltri rineted hydrocarbon containing 65 per cen Formulation 1 suflicient water to make a total volume of Oil liter.

I The number of tests carried out on each formulation was five, except in TOTA-3 and TOTA-4 where ten tests were run. The dosage was the same for each test, 3.0 grams per 1000 cubic feet.

Acording to the foregoing data obtained with typical aerosol-type formulations, synergized cyclethriu formulations are in every instance superior to similar synergized allethrin formulations.

A through D (cyclethrln) E through E (allethrin) I through K (cyclethrin) L through 0 (allethrin) P through R (cyclethrin) S through U (allethrin).----

EXAMLLE 15 According to the foregoing results, cyclethrin is activated by synergists 264 and 6266 to a greater extent than is allethrin. I

EXAMPLE 16 The toxicity to rice weevil was determined for cyclethrin alone, and cyclethrin synergized with sulfoxide, piperonyl butoxide and sulfone.

The efiicacy against Mexican bean beetle larvae on tendergreen bean was determined for cyclethrin alone and cyclethrin synergized with synergist MGK 264, (N-2- (ethylhexy) bicyclo [2,2,1]-5-heptene-2,3-dicarboximide) and synergist 6266 (N-(hexoxyethoxypropyl)-bicyclo[2,2,1]-5-heptene-2,3-dicarboximide). Similar tests 5 were also run with allethrin and pyrethrins.

Preparation of formulations and spraying of plants was For purposes of comdone by the method employed in evaluating cyclethrin PafiSOIl Similar tests were made with allmhl'in, ullsyllel" on bean aphid (Example 11). Two bean plants were m syrfergized- In Preparing the formulations the used per concentration. After plants had been sprayed f mgr ed1ent or active ingredient P .Synergist was and were thoroughly dry, each plant was enclosed in a dissolved m acetone An dust m fins-case wheat spherical screened cage in which four third instar larvae dust was then add-ed to hung the total welght 100 h d b 1 1 6d grams. The materlals were then thoroughly mixed-to a @611 PWVIOus Y P ac Test Plants and Insects Were lHSllIe uniformity and the acetone allowed to evaporate kept under fluorescent light at room temperature. Counts completely from the mixture. The formulation was again v21 thoroughlymixedon a ball for one-halfhour. The formulations are given in the following table:

butyl ether (viscosity at 100 F.; 100 S.U.S.;. average molecular weight about 850) known commercially as l i l r "W rm! li/1H i Material A B O D E F G H Cyclethrin, milli r m 500 100 100 100 Allethrin, milligrams 500 100 100 100 Piperonyl butoxide, milligrams 1, 600 1, 600 Bulioxide, mjlligrams 1, 600 1, 600 Sulionamilli r m 1,600 1,600 Inert diluentlwheat dust) grams 99. 5 99. 5 98. 3 98. 3 98. 3 98. 3 98. 3 98. 3

The above formulations were placed in four ounce bottles containing two ounces of wheat and the contents mixed by shaking for one-half hour. One hundred adult Crag Fly Rep'ellant was tested.

rice weevils were then introduced into each bottle and Formulation A B 0T allowed to feed for a period of one week. Mortality I 1 counts were taken at the end of this exposure. Dosage cycletmm, mmigmms 84 series tests were run and the results plotted on log proballethrn}, r

r pyrethrms, milligrams. 100 abllity paper. The results for seven day mortality 111 Fly repenantymmmter 10 terms of lethal dose for 50 percent kill were as follows: deodorized kerosene, te s----- 0 90 90 Dosage re- Large group Feet-Grady test results quired for 50 Formulation percent kill within seven Percent OTI Difierence ays, No. of Percent Knockmilhgrams 0 Formulation Tests Kill, down,

3 24Hrs. 10min. 11111 Knockdown A (cyclethrin) 500 B (allethrin) 260 C (cyclethrin) 70 A. cyclethrin 3 84. 96. 8 +40 +0.3 D (cyclethrin 50 B. allethri 3 73. 2 98.1 +29 +1.6 E (cyelethrin) 52 OT 6 44.0 96. 5 F (allethrin) 62 G (allethrin) 58 e 51 The results of this test show that the plus value for According to the foregoing results, cyclethrin, although only one-third as effective as allethrin when used alone, is activated or synergized to a greater degree than is allethrin by the synergists employed. Under actual use conditions, both allethrin and cyclethrin would be used with synergists because of the prohibitive cost of these compounds if used unsynergized. Cyclethrin, because of its freedom from mammalian toxicity, has the advantage that it can be used to protect grain products.

EXAMPLE 17 Dosage Required for 50 Formulation percent Kill (LD-50) in 48 hrs., parts per million Allethrin 0. 08 Cyclethrin 0.07 Allethrin-i-sulfoxide 1 0. 046 Oyclethrin+sulf0xide t 0. 043 Untreated checks 0 1 1 part a1lethrin+5 parts sulfoxide. Z 1 part eyclethrin-l-i parts sulioxide.

EXAMPLE 18 The synergistic effect of polyoxypropylene glycol monokill of synergized cyclethrin compared with OTI is better by +11 percentage points than a similar comparison of synergized allethrin; while the knockdown is only slightly less favorable by -1.3 percentage point.

What is claimed is:

1. As a new composition of matter, 3-(2-cyclopentenyl)-2-methyl-4-oXo-2-cyclopentenyl chrysanthemummonocarboxylate, represented by the graphic formula,

2. As a new composition of matter, a lower alkyl 4- (2-cyclopentenyl)-3-ketobutyrate, represented by the graphic formula,

CH=CH i7HCI-I C O (EH 0 0 O-lower alkyl CHg- Hg 3. As a new composition of matter, 4-(2-cyclopentenyl)-3-ketobutyric acid and its alkali metal salt, represented by the graphic formula,

OH=CH 1101120 0 OH C 0 OX Hg- Hg where X is of the group consisting of hydrogen and an alkali metal.

4. In a process for making 3-(2-cyclopentenyl)-2- methyl-4-oxo-2-cyclopenteny1 chrysenthemumate the steps which include reacting rcyclopentadiene with hydrogen chloride to produce 2-cyclopentenyl chloride; reacting acetoacetic ester with 2-cyclopenteny1 chloride in the presence of an equivalent amount of alkali metal alcoholate to produce a lower alkyl 2-(2-cyclopentenyl) -3-keto butyrate; subjecting the 2-(2-cyclopentenyl)-3-ketobutyrate to ketonic hydrolysis in the presence of alkali metal hydroxide to form 2-cyclopentenyl acetone; reacting the 2- cyclopentenyl acetone with diethyl carbonate in the presence of alkali metal alcoholate to form ethyl 4-(2- cyclopentenyD-3-ketobutyrate; converting the ethyl 4-(2- cyclopcntenyD-3-ketobutyrate to the alkali metal salt and reacting it with pyruvic aldehyde to make 6-(2-cyclopentenyl)-3-hydroXyheXane-2,5-dione; treating the 6-(2- cyclopentenyl)-3-hydroxyhexane-2,5-dione with dilute alkali to convert it to 2-(2-cyclopenteyl)-3-methyl-2- cyclopenten-4-ol-l-one; and reacting the 2-(2-cyclopentenyl)-3-methyl-2-cyclopenten-4-ol-l-one with chrysanthemummonocarboxylic anhydride to form the ester thereof.

5. In a process for making an intermediate useful for the production of 3-(2-cyc1opentenyl)-2-methyl-4-oxo-2- cyclopentenyl chrysanthemumate, the step which comprises heating to the reaction temperature thereof a mixture of 2-cyclopentenyl acetone and diethyl carbonate in the presence of sodium ethoxide as catalyst to produce ethyl 4-(2-cycl0pentenyl) -3-ketobutyrate.

6. An insecticidal composition comprising 3-(2-cyclopentenyl)-2-methyl 4-oxo 2 cyclopentenyl chrysanthemummonocarboxylate and an inert carrier therefor.

7. The method of controlling insects which comprises applying 3- (Z-cyclopentenyl) -2-methyl-4-oXo-2-cyclopentenyl chrysanthemumate to a base.

5 References Cited in the file of this patent UNITED STATES PATENTS 2,228,256 Christiansen Jan. 14, 1941 2,446,570 Bludworth et a1. Aug. 10, 1948 10 2,453,619 Byrns Nov. 9, 1948 2,491,442 Coleman Dec. 13, 1949 2,506,636 Flenner May 9, 1950 2,510,870 Dieter et al. June 6, 1950 2,535,086 Mofiett et al. Dec. 26, 1950 15 2,603,652 Schechter July 15, 1952 2,768,965 Stansbury et al. Oct. 30, 1956 OTHER REFERENCES Richter: Textbook of Organic Chemistry, pp. 368-9,

20 J. Wiley (1952).

Wagner et al.: Synthetic Organic Chemistry, p. 488,

I. Wiley (1953). 

1. AS A NEW COMPOSITION OF MATTER,3-(2-CYCLOPENTENYL)-2METHYL-4-OXO-2 CYCLOPENTENYL CHRYSANTHEMUMMONOCARBOXYLATE, REPRESENTED BY THE GRAPHIC FORMULA,
 7. THE METHOD OF CONTROLLING INSECTS WHICH COMPRISES APPLYING 3-(2-CYCLOPENTENY)-2-METHYL-4-OXO-2-CYCLOPENTENYL CHRYSANTHEMUMATE TO A BASE. 